Medical instruments and techniques for thermally-mediated therapies

ABSTRACT

A surgical instrument for thermally-mediated therapies in targeted tissue volumes and for causing thermal effects in polymer tissue-contacting members. In one embodiment, the instrument has a working end with an interior chamber that is supplied with a biocompatible liquid. An energy source causes a liquid-to-vapor phase change within the interior of the instrument. The vapor phase media then is ejected from the working surface of the instrument, and a controlled vapor-to-liquid phase change in an interface with tissue applies thermal energy substantially equal to the heat of vaporization to ablate tissue. The vapor-to-liquid phase transitions, or internal energy releases, can be provided about thin-film flexible structures for engaging body lumens and cavities. An exemplary embodiment can be used for shrinking, sealing, welding or creating lesions in tissue—while causing limited collateral thermal damage and while totally eliminating electrical current flow in the engaged tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of Provisional U.S. Patent ApplicationSer. No. 60/416,622 filed Oct. 7, 2002. This application also is acontinuation-in-part of U.S. patent application Ser. No. 10/017,582filed Dec. 7, 2001, now U.S. Pat. No. 6,669,694 which claims benefit ofProvisional Patent Application Ser. No. 60/254,487 filed Dec. 9, 2000.All of the above applications are incorporated herein by this reference,together with the specifications of all other commonly-inventedapplications cited therein.

FIELD OF THE INVENTION

This invention relates to surgical instruments for thermally-mediatedtreatments of tissue, and more particularly relates to a system forshrinking, sealing, welding or creating lesions in tissue by means ofinjection of a thermal energy laden vapor media into a body structurewherein the vapor-to-liquid phase change of the media applies energy tothe tissue.

BACKGROUND OF THE INVENTION

Various types of radiofrequency (Rf) and laser surgical instruments havebeen developed for delivering thermal energy to tissue, for example tocause hemostasis, to weld tissue or to cause a thermoplastic remodelingof tissue. While such prior art forms of energy delivery work well forsome applications, Rf and laser energy typically cannot cause highly“controlled” and “localized” thermal effects that are desirable inmicrosurgeries or other precision surgeries. In general, the non-linearor non-uniform characteristics of tissue affect both laser and Rf energydistributions in tissue. The objective of sealing or welding tissuerequires means for elevating the tissue temperature uniformly throughouta targeted site.

What is needed is an instrument and technique (i) that can controllablydeliver thermal energy to non-uniform tissue volumes; (i) that canshrink, seal, weld or create lesions in selected tissue volumes withoutdesiccation or charring of adjacent tissues; (iii); and (iv) that doesnot cause stray electrical current flow in tissue.

SUMMARY OF THE INVENTION

The present invention is adapted to provide improved methods ofcontrolled thermal energy delivery to localized tissue volumes, forexample for sealing, welding or thermoplastic remodeling of tissue. Ofparticular interest, the method causes thermal effects in targetedtissue without the use of Rf current flow through the patient's body.

In general, the thermally-mediated treatment method comprises causing avapor-to-liquid phase state change in a selected media at a targetedtissue site thereby applying thermal energy substantially equal to theheat of vaporization of the selected media to said tissue site. Thethermally-mediated therapy can be delivered to tissue by suchvapor-to-liquid phase transitions, or “internal energy” releases, aboutthe working surfaces of several types of instruments for endoluminaltreatments or for soft tissue thermotherapies. FIGS. 1A and 1Billustrate the phenomena of phase transitional releases of internalenergies. Such internal energy involves energy on the molecular andatomic scale—and in polyatomic gases is directly related tointermolecular attractive forces, as well as rotational and vibrationalkinetic energy. In other words, the method of the invention exploits thephenomenon of internal energy transitions between gaseous and liquidphases that involve very large amounts of energy compared to specificheat.

It has been found that the controlled application of internal energiesin an introduced media-tissue interaction solves many of the vexingproblems associated with energy-tissue interactions in Rf, laser andultrasound modalities. The apparatus of the invention provides afluid-carrying chamber in the interior of the device or working end. Asource provides liquid media to the interior chamber wherein energy isapplied to instantly vaporize the media. In the process of theliquid-to-vapor phase transition of a saline media in the interior ofthe working end, large amounts of energy are added to overcome thecohesive forces between molecules in the liquid, and an additionalamount of energy is requires to expand the liquid 1000+ percent (PΔD)into a resulting vapor phase (see FIG. 1A). Conversely, in thevapor-to-liquid transition, such energy will be released at the phasetransitions at the targeted tissue interface. That is, the heat ofvaporization is released in tissue when the media transitioning fromgaseous phase to liquid phase wherein the random, disordered motion ofmolecules in the vapor regain cohesion to convert to a liquid media.This release of energy (defined as the capacity for doing work) relatingto intermolecular attractive forces is transformed into therapeutic heatfor a thermotherapy within a targeted body structure. Heat flow and workare both ways of transferring energy.

In FIG. 1A, the simplified visualization of internal energy is usefulfor understanding phase transition phenomena that involve internalenergy transitions between liquid and vapor phases. If heat were addedat a constant rate in FIG. 1A (graphically represented as 5 calories/gmblocks) to elevate the temperature of water through its phase change toa vapor phase, the additional energy required to achieve the phasechange (latent heat of vaporization) is represented by the large numberof 110+ blocks of energy at 100° C. in FIG. 1A. Still referring to FIG.1A, it can be easily understood that all other prior art ablationmodalities—Rf, laser, microwave and ultrasound—create energy densitiesby simply ramping up calories/gm as indicated by the temperature rangefrom 37° C. through 100° C. as in FIG. 1A. The prior art modalities makeno use of the phenomenon of phase transition energies as depicted inFIG. 1A.

FIG. 1B graphically represents a block diagram relating to energydelivery aspects of the present invention. The system provides forinsulative containment of an initial primary energy-media within aninterior chamber of an instrument's working end. The initial, ascendantenergy-media interaction delivers energy sufficient to achieve the heatof vaporization of a selected liquid media such as saline within aninterior of the instrument body. This aspect of the technology requiresan inventive energy source and controller—since energy application fromthe source to the selected media (Rf, laser, microwave etc.) must bemodulated between very large energy densities to initially surpass thelatent heat of vaporization of the media within milliseconds, andpossible subsequent lesser energy densities for maintaining the media inits vapor phase. Additionally, the energy delivery system is coupled toa pressure control system for replenishing the selected liquid phasemedia at the required rate—and optionally for controlling propagationvelocity of the vapor phase media from the working end surface of theinstrument. In use, the method of the invention comprises the controlleddeposition of a large amount of energy—the heat of vaporization as inFIG. 1A—when the vapor-to-liquid phase transition is controlled at thevapor media-tissue interface. The vapor-to-liquid phase transitiondeposits about 580 cal/gram within the targeted tissue site to performthe thermal ablation.

This new ablation modality can utilize specialized instrument workingends for several cardiovascular therapies or soft tissue ablationtreatments for tissue sealing, tissue shrinkage, tissue ablation,creation of lesions or volumetric removal of tissue. In general, theinstrument and method of the invention advantageously cause thermalablations rapidly and efficiently compared to conventional Rf energydelivery.

The instrument and method of the invention generate vapor phase mediathat is controllable as to volume and ejection pressure to provide anot-to-exceed temperature level that prevents desiccation, eschar, smokeand tissue sticking;

The instrument and method of the invention cause an energy-tissueinteraction that is imageable with intraoperative ultrasound or MRI;

The instrument and method of the invention advantageously cause thermaleffects in tissue that do not rely applying an electrical field acrossthe tissue to be treated; and

The instrument and method of the invention advantageously createsthermal effects in a targeted tissue volume with substantiallycontrolled lateral margins between the treated tissue and untreatedtissue.

Additional advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a graphical depiction of the quantity of energy needed toachieve the heat of vaporization of water.

FIG. 1B is a diagram of phase change energy release that underlies onemethod of the invention.

FIG. 2A is a perspective view of the working end of an exemplary Type“A” probe of the present invention with an openable-closeable tissueengaging structure in a first open position.

FIG. 2B is a perspective view similar to FIG. 2A probe of the presentinvention in a second closed position.

FIG. 3 is a cut-away view of the working end of FIGS. 2A-2B.

FIG. 4 is a perspective view of the working end of FIG. 3 capturing anexemplary tissue volume.

FIGS. 5-6 are sectional schematic views of working end of FIG. 3depicting, in sequence, the steps of a method of the present inventionto seal or weld a targeted tissue volume, FIG. 5 illustrating thepressurized delivery of a liquid media to an interior channel, and FIG.6 depicting an electrical discharge that causes a liquid-to-gas phasechange as well as the ejection of the vapor media into the targetedtissue to cause a thermal weld.

FIG. 7 is a perspective view of an alternative working end of thepresent invention.

FIG. 8 is a sectional view of the working end of FIG. 7 showing amicrochannel structure.

FIG. 9 is a greatly enlarged sectional view of the microchannelstructure of FIG. 8 depicting the electrode arrangement carried therein.

FIG. 10 is a schematic sectional view of an alternative working end witha helical electrode arrangement in the interior chamber.

FIG. 11 illustrates a method of the invention in treating a blood vesseldisorder with the device of FIG. 10.

FIG. 12 illustrates an alternative method for treating an aneurysm.

FIG. 13 illustrates the method of treating an aneurysm as in FIG. 12.

FIG. 14 is a perspective view of an alternative working end of a Type“B” embodiment with a plurality of microchanneled structures in acatheter.

FIG. 15 is a perspective view of an alternative working end withapertures in the surface of an expandable structure.

FIG. 16 is a cut-away view of the working end of a FIG. 15.

FIG. 17 is a plan view of an alternative working end with apertures inthe surface of a thin-film structure for engaging and collapsing in abody cavity.

FIG. 18A is a view of a method of fabricating the thin-film structure ofFIG. 17.

FIG. 18B is another view of a method of fabricating the thin-filmstructure of FIG. 17.

FIG. 19 illustrates the thermotherapy method utilizing the thin-filmstructure of FIG. 17.

FIG. 20A is a plan view of an alternative working end.

FIG. 20B depicts a greatly enlarged schematic view of the thin-filmstructure of FIG. 20A showing electrical energy delivery to conductivevapor media injected deep into a soft tissue volume.

FIG. 21 is a schematic view of an alternative instrument working end forsealing/transecting tissue with a jaw structure that carries areleasable weldable polymer clip of a bioresorbable composition.

FIG. 22A is a schematic view of the working end and polymer clip of FIG.21 depicting a first step in its method of use being clamped around ablood vessel and welded at the clip's free ends.

FIG. 22B is a schematic view of the polymer clip of FIG. 22A depictingthe next step in its method of use wherein a vapor media is ejectedthrough the polymer clip to seal the tissue and shrink the polymer.

DETAILED DESCRIPTION OF THE INVENTION

1. Type “A” Thermotherapy Instrument. Referring to FIGS. 2A, 2B and 3,the working end 10 of a Type “A” system 5 of the present invention isshown that is adapted for endoscopic procedures in which a tissue volumeT targeted for treatment (a thermoplasty) can be captured by a loopstructure. The working end 10 comprises a body 11 of insulator material(see FIG. 3) coupled to the distal end of introducer member 12 extendingalong axis 15. In this exemplary embodiment, the working end 10 has agenerally cylindrical cross-section and is made of any suitable materialsuch as plastic, ceramic, glass, metal or a combination thereof. Theworking end 10 is substantially small in diameter (e.g., 2 mm to 5 mm)and in this embodiment is coupled to an elongate flexible introducermember 12 to cooperate with a working channel in an endoscope.Alternatively, the working end 10 may be coupled to a rigid shaft memberhaving a suitable 1 mm to 5 mm or larger diameter to cooperate with atrocar sleeve for use in endoscopic or microsurgical procedures. Aproximal handle portion 14 of the instrument indicated by the blockdiagram of FIG. A carries the various actuator mechanisms known in theart for actuating components of the instrument.

In FIGS. 2A, 2B and 3, it can be seen that the working end 10 carries anopenable and closeable structure for capturing tissue between a firsttissue-engaging surface 20A and a second tissue-engaging surface 20B. Inthis exemplary embodiment, the working end 10 and first tissue-engagingsurface 20A comprises a non-moving component indicated at 22A that isdefined by the exposed distal end of body 11 of working end 10. Thesecond tissue-engaging surface 20B is carried in a moving component thatcomprises a flexible loop structure indicated at 22B.

The second moving component or flexible loop 22B is actuatable by aslidable portion 24 a of the loop that extends through a slot 25 in theworking end to an actuator in the handle portion 14 as is known in theart (see FIG. 3). The other end 24 b of the loop structure 22B is fixedin body 11. While such an in-line (or axial) flexible slidable member ispreferred as the tissue-capturing mechanism for a small diameterflexible catheter-type instrument, it should be appreciated that anyopenable and closable jaw structure known in the art falls within thescope of the invention, including forms of paired jaws with cam-surfaceactuation or conventional pin-type hinges and actuator mechanisms. FIG.2A illustrates the first and second tissue-engaging surfaces 20A and 20Bin a first spaced apart or open position. FIG. 2B shows the first andsecond surfaces 20A and 20B moved toward a second closed position.

Now turning to the fluid-to-gas energy delivery means of the invention,referring to FIG. 3, it can be seen that the insulated or non-conductivebody 11 of working end 10 carries an interior chamber indicated at 30communicating with lumen 33 that are together adapted for delivery andtransient confinement of a fluid media M that flows into chamber 30. Thechamber 30 communicates via lumen 33 with a fluid media source 35 thatmay be remote from the device, or a fluid reservoir (coupled to a remotepressure source) carried within introducer 12 or carried within a handleportion 14. The term fluid or flowable media source 35 is defined toinclude a positive pressure inflow system which may be a syringe, anelevated remote fluid sac that relies on gravity, or any suitablepump-type pressure means known in the art. The fluid delivery lumen 33transitions to chamber 30 at proximal end portion 34 a thereof. Thedistal end portion 34 b of chamber 30 has a reduced cross-section to(optionally) function as a jet or nozzle indicated at 38.

Of particular interest, still referring to FIG. 3, paired electrodeelements 40A and 40B with exposed surfaces and that are spaced apart insurface 42 of the interior fluid confinement chamber 30. In thisexemplary embodiment, the electrode elements 40A and 40B comprisecircumferential exposed surfaces of a conductive material positioned atopposing proximal and distal ends of interior chamber 30. It should beappreciated that the method of the invention of may utilize any suitableconfiguration of spaced apart electrodes (e.g., spaces apart helicalelectrode elements or porous electrodes) about at least one confinementchamber 30 or lumen portion. Alternatively, each electrode can be asingular projecting element that projects into the chamber. Theexemplary embodiment of FIG. 3 shows an elongate chamber having an axialdimension indicated at A and diameter or cross-section indicated at B.The axial dimension may range from about 0.1 mm to 20.0 mm and may besingular or plural as described below. The diameter B may range frommicron dimensions (e.g., 0.5 μm) for miniaturized instruments to alarger dimension (e.g., 5.0 mm) for larger instruments for causing thethermally induced fluid-to-gas transformation required to enable thenovel phase change energy-tissue interaction of the invention. Theelectrodes are of any suitable material such as aluminum, stainlesssteel, nickel titanium, platinum, gold, or copper. Each electrodesurface preferably has a toothed surface texture indicated at 43 thatincludes hatching, projecting elements or surface asperities for betterdelivering high energy densities in the fluid proximate to theelectrode. The electrical current to the working end 10 may be switchedon and off by a foot pedal or any other suitable means such as a switchin handle 14.

FIG. 3 further shows that a preferred shape is formed into thetissue-engaging surface 20A to better perform the method of fusingtissue. As can be seen in FIGS. 2B and 3, the first tissue-engagingsurface 20A is generally concave so as to be adapted to receive agreater tissue volume in the central portion of surface 20A. The secondtissue-engaging surface 20B is flexible and naturally will be concave inthe distal or opposite direction when tissue is engaged between surfaces20A and 20B. This preferred shape structure allows for controllablecompression of the thick targeted tissue volumes T centrally exposed tothe energy delivery means and helps prevent conductance of thermaleffects to collateral tissue regions CT (see FIG. 4) and as will bedescribed in greater detail below.

FIGS. 2A and 3 show that first tissue-engaging surface 20A defines anopen structure of at least one aperture or passageway indicated at 45that allows vapor pass therethrough. The apertures 45 may have anycross-sectional shape and linear or angular route through surface 20Awith a sectional dimension C in this embodiment ranging upwards frommicron dimensions (e.g., 0.5 μm) to about 2.0 mm in a large surface 20A.The exemplary embodiment of FIG. 3 has an expanding cross-sectiontransition chamber 47 proximate to the aperture grid that transitionsbetween the distal end 34 b of chamber 30 and the apertures 45. However,it should be appreciated that such a transition chamber 47 is optionaland the terminal portion of chamber 30 may directly exit into aplurality of passageways that each communicate with an aperture 45 inthe grid of the first engaging surface 20A. In a preferred embodiment,the second tissue-engaging surface 20B defines (optionally) a grid ofapertures indicated at 50 that pass through the loop 22B. Theseapertures 50 may be any suitable dimension (cf. apertures 45) and areadapted to generally oppose the first tissue-engaging surface 20A whenthe surfaces 20A and 20B are in the second closed position, as shown inFIG. 2B.

The electrodes 40A and 40B of working end 10 have opposing polaritiesand are coupled to electrical generator 55. FIG. 3 showscurrent-carrying wire leads 58 a and 58 b that are coupled to electrodes40A and 40B and extend to electrical source 55 and controller 60. In apreferred embodiment of the invention, either tissue-engaging surfaceoptionally includes a sensor 62 (or sensor array) that is in contactwith the targeted tissue surface (see FIG. 2A). Such a sensor, forexample a thermocouple known in the art, can measure temperature at thesurface of the captured tissue. The sensor is coupled to controller 60by a lead (not shown) and can be used to modulate or terminate powerdelivery as will be described next in the method of the invention.

Operation and use of the working end of FIGS. 2A, 2B and 3 in performinga method of treating tissue can be briefly described as follows, forexample in an endoscopic polyp removal procedure. As can be understoodfrom FIG. 4, the working end 10 is carried by an elongate catheter-typemember 12 that is introduced through a working channel 70 of anendoscope 72 to a working space. In this case, the tissue T targeted forsealing is a medial portion 78 of a polyp 80 in a colon 82. It can beeasily understood that the slidable movement of the loop member 22B cancapture the polyp 80 in the device as shown in FIG. 4 after beinglassoed. The objective of the tissue treatment is to seal the medialportion of the polyp with the inventive thermotherapy. Thereafter,utilize a separate cutting instrument is used to cut through the sealedportion, and the excised polyp is retrieved for biopsy purposes.

Now turning to FIGS. 5 and 6, two sequential schematic views of theworking end engaging tissue T are provided to illustrate theenergy-tissue interaction caused by the method of the invention. FIG. 5depicts an initial step of the method wherein the operator sends asignal to the controller 60 to delivery fluid media M (e.g., salinesolution or sterile water) through lumen 33 into chamber 30. FIG. 6depicts the next step of the method wherein the controller delivers anintense discharge of electrical energy to the paired electrode elements40A and 40B within chamber 30 indicated by electric arc or electricfield EF. The electrical discharge provides energy exceeding the heat ofvaporization of the contained fluid volume. The explosive vaporizationof fluid media M (of FIG. 5) into a vapor or gas media is indicated atM′ in FIG. 6. The greatly increased volume of gas media M′ results inthe gas being ejected from chamber 30 at high velocity through apertures45 of surface 20A into the targeted tissue T. The liquid to gasconversion caused by the electrical discharge also heats the gas mediaM′ to about 100° C. to deliver thermal effects into tissue T, or eventhrough the targeted tissue T, as indicated graphically by the shadedregions of gas flow in FIG. 6. The fluid source and its pressure or pumpmechanism can provide any desired level of vapor ejection pressure.Depending on the character of the introduced liquid media, the media isaltered from a first lesser temperature to a second greater temperaturein the range of 100° C. or higher depending on pressure. The ejection ofvapor media M′ will uniformly elevate the temperature of the engagedtissue to the desired range of about 65° C. to 100° C. very rapidly tocause hydrothermal denaturation of proteins in the tissue, and to causeoptimal fluid intermixing of tissue constituents that will result in aneffective seal. In effect, the vapor-to-liquid phase transition of theejected media M′ will deposit heat equal to the heat of vaporization inthe tissue. At the same time, as the heat of vaporization of media M′ isabsorbed by water in the targeted tissue, the media converts back to aliquid thus hydrating the targeted tissue T. It is believed that suchprotein denaturation by hydrothermal effects differentiates this methodof tissue sealing or fusion from all other forms of energy delivery,such as radiofrequency energy delivery. All other forms of energydelivery vaporize intra- and extracellular fluids and cause tissuedesiccation, dehydration or charring which is undesirable for theintermixing of denatured tissue constituents into a proteinaceousamalgam.

The above electrical energy deliver step is repeated at a highrepetition rate to cause a pulsed form of thermal energy delivery in theengaged tissue. The fluid media M inflow may be continuous or pulsed tosubstantially fill chamber 30 before an electrical discharge is causedtherein. The repetition rate of electrical discharges may be from about1 Hz to 1000 Hz. More preferably, the repetition rate is from about 10Hz to 200 Hz. The selected repetition rate preferably provides aninterval between electrical discharges that allows for thermalrelaxation of tissue, that may range from about 10 ms to 500 ms. Theelectrical source or voltage source 55 may provide a voltage rangingbetween about 100 volts and 10,000 volts to cause instant vaporizationof the volume of fluid media M captured between the electrode elements40A and 40B. After a selected time interval of such energy applicationto tissue T, that may range from about 1 second to 30 seconds, andpreferably from about 5 to 20 seconds, the engaged tissue will becontain a core region in which the tissue constituents are denatured andintermixed under relatively high compression between surfaces 20A and20B. Upon disengagement and cooling of the targeted tissue T, thetreated tissue will be fused or welded. Over time, the body's woundhealing response will reconstitute the treated tissue with an intermixedcollagenous volume or scar-like tissue.

An optional method of controlling the repetition rate of electricaldischarges comprises the measurement of electrical characteristics ofmedia M within the chamber 30 to insure that the chamber is filled withthe fluid media at time of the electrical discharge. The electricalmeasurement then would send a control signal to the controller 60 tocause each electrical discharge. For example, the liquid media M can beprovided with selected conductive compositions in solution therein. Thecontroller 60 then can send a weak electrical current between the pairedelectrodes 40A and 40B and thereafter sense the change in an impedancelevel between the electrodes as the chamber 30 is filled with fluid togenerate the control signal.

Referring to FIG. 7, a working end 210 of an alternative instrument 205of the present invention is depicted. The phase transitional energydelivery aspects of the invention are the same as described above. Theinstrument 205 differs in that it utilizes significantly reduceddimensions (or micronization) of features in the working end 210. Moreparticularly, a fluid media source 235A and pressure control system 235Bare adapted to provide pressurized flows of liquid media M through theintroducer body 211 and thereafter into microchannel body or structureindicated at 215 (see FIG. 8). The microchannel or microporous bodydefines therein plurality of small diameter fluid passageways ormicrochannel portions 216 (collectively). The microchannel body 215 alsocan be a microporous trabecular material to provide open-cell flowpassageways therethrough.

In FIG. 8, it can be seen that the microchannel body 215 comprises astructure of an electrically insulative material (or a conductivematerial with an insulative coating) that defines open flow passagewaysor channels 216 therethrough that have open terminations or ports 218 inthe working surface 220. At an interior of the microchannel body 215, anintermediate region of the open flow channels 216 is exposed to firstand second electrode elements 240A and 240B. The electrode elements 240Aand 240B can be formed in a plates or layers of channeled material ortrabecular material that extends transverse to passageways 216. Thus,the channels are exposed to surfaces of the electrode elements 240A and240B interior of the working surface 220 that interfaces with thetargeted tissue T. As depicted in FIG. 9, electrical energy is appliedbetween the electrodes to cause vaporization of the inflowing liquidmedia M which is converted to a vapor media M′ within the interior ofthe channels 216 for ejection from the working surface 220 to interactwith tissue as described above.

A working end similar to that of FIGS. 7-8 can be used in variousthermotherapy procedures. For example, a rigid probe can be used inorthopedic procedures to cause hydrothermal shrinkage of collagen, forexample in a spinal disc, or a joint capsule to stabilize the joint (seeU.S. patent application Ser. No. 09/049,711 filed Mar. 27, 1998,incorporated herein by this reference). In an arthroscopic procedure,the working end is painted across a targeted tissue site in a jointcapsule to shrink tissue. In another procedure, the working end may bestabilized against any collagenous tissue to heat and shrink collagen ina targeted tissue such as a herniated disc. In another procedure, theworking end can be painted across the surface of a patient's esophagusto ablate abnormal cells to treat a disorder known as Barrett'sesophagus. As described previously, the thermal energy delivery means ofthe invention preferably uses an electrical energy source and spacedapart electrodes for flash vaporization of a liquid media. It should beappreciated that a resistive element coupled to an electrical sourcealso can be used. For example, a resistive element can fabricated out ofany suitable material such a tungsten alloy in a helical, tubular or amicroporous form that allows fluid flow therethrough.

Now referring to FIGS. 10 and 11, another embodiment of instrumentworking end 300 is shown in schematic sectional view. The previousdevices were shown and optimized for having a working surface thatengages tissue, and for controlling and limiting thermal effects inengaged tissue. In the embodiment of FIG. 10, the working end is adaptedfor controlled application of energy by means of phase change energyrelease in an endovascular application, or in media within or aboutother body lumens, ducts and the like.

FIG. 10 illustrates the working end 300 of a member or catheter body 305that is dimensioned for introduction into a patient's vasculature orother body lumen. The diameter of body 305 can range from about 1 Fr. to6 Fr. or more. The working end 300 typically is carried at the distalend of a flexible catheter but may also be carried at the distal end ofa more rigid introducer member. In a rigid member, the working end alsocan be sharp for penetrating into any soft tissue (e.g. a fibroid,breast lesion or other organ such as a prostate) or into the lumen of avessel.

The working end 300 of FIG. 10 has an interior chamber 310 again incommunication with fluid media inflow source 335A and pressure controlsystem 335B. The interior chamber 310 carries opposing polarityelectrodes 315A and 315B as thermal energy emitters. The distal terminusor working surface 320 of the catheter has media entrance port 322therein. In this embodiment, the electrodes 315A and 315B are spacedapart, indicated with (+) and (−) polarities coupled to electricalsource 355, and are of a flexible material and configured in anintertwined helical configuration to provide a substantially largesurface area for exposure to inflowing fluid media M. The electrodes canextend axially from about 1 mm to 50 mm and are spaced well inward, forexample from 1 mm to 100 mm from the distal working surface 320. Thistype of electrode arrangement will enhance energy delivery to the liquidmedia M to allow effective continuous vaporization thereof. The lumen orchamber portion between electrodes 315A and 315B allows for focusedenergy application to create the desired energy density in the inflowingmedia M to cause its immediate vaporization. The vapor is thenpropagated from the working surface 320 via port 322 to interact withthe endoluminal media. It should be appreciated that the instrument mayhave a plurality of media entrance ports 322 in the working surface, oradditionally the radially outward surfaces of the catheter.

In the system embodiment of FIG. 10, the electrodes 315A and 315B arecoupled to electrical source 355 by leads 356 a and 356 b. The workingend 300 also is coupled to fluid media source 335A that carriespressurization means of any suitable type together with a pressurecontrol system indicated at 335B.

In FIG. 11, the method of the invention is shown graphically wherein thedistal end 300 is introduced into vasculature for the purpose ofcreating thermal effects in the vessel walls 360. In one targetedendovascular procedure, as depicted in FIG. 11, the objective is toapply controlled thermal energy to tissue to shrink and/or damage vesselwalls to treat varicose veins. Most endothelial-lined structures of thebody, such as blood vessel and other ducts, have substantially collagencores for specific functional purposes. Intermolecular cross-linksprovide collagen connective tissue with unique physical properties suchas high tensile strength and substantial elasticity. A well-recognizedproperty of collagen relates to the shrinkage of collagen fibers whenelevated in temperature to the range 60° to 80° C. Temperature elevationruptures the collagen ultrastructural stabilizing cross-links, andresults in immediate contraction in the fibers to about one-third oftheir original longitudinal dimension. At the same time, the caliber ofthe individual collagen fibers increases without changing the structuralintegrity of the connective tissue.

As represented in FIG. 11, the delivery of energy from the electrodes315A and 315B to an inflow of liquid media M, such as any salinesolution, will cause its instant vaporization and the expansion of thevapor (in addition to pressure from pressure source 335B) will causehigh pressure gradients to propagate the heated vapor from port 322 tointeract with endovascular media. The pressurized fluid media source335A and pressure control subsystem 335B also can be adapted to create apressure gradient, or enhance the pressure gradients caused by vaporexpansion, to controllably eject the heated vapor from the workingsurface 320. As depicted in FIG. 11, the vaporized media M′ depositsenergy to the vessel walls in the vapor to liquid phase change energyrelease. The vaporized media is at about 100° C. as it crosses theinterface between the working surface 320 and blood and will push theblood distally while at the same time causing the desired thermaleffects in the vessel wall 360.

As shown in FIG. 11, the collagen in the vessel walls will shrink and/ordenature (along with other proteins) to thereby collapse the vessel.This means of applying thermal energy to vessel walls can controllablyshrink, collapse and occlude the vessel lumen to terminate blood flowtherethrough, and offers substantial advantages over alternativeprocedures. Vein stripping is a much more invasive treatment. Rf closureof varicose veins is known in the art. Typically, a catheter device ismoved to drag Rf electrodes along the vessel walls to apply Rf energy todamage the vessel walls by means of causing ohmic heating. Such Rf ohmicheating causes several undesirable effects, such as (i) creating highpeak electrode temperatures (up to several hundred degrees C.) that candamage nerves extending along the vessel's exterior, (ii) causingnon-uniform thermal effects about valves making vessel closureincomplete, and (iii) causing vessel perforations as the catheterworking end is dragged along the vessel walls. In contrast, the energydelivery system of the invention utilizes the heat of a vapor media thatcannot exceed about 100° C. (or slightly higher depending on pressure)to apply energy to the vessel walls. This method substantially preventsheat from being propagated heat outwardly by conduction—thus preventingdamage to nerves. There is no possibility of causing ohmic heating innerves, since a principal advantage of the invention is the applicationof therapeutic heat entirely without electrical current flow in tissue.Further, the vapor and its heat content can apply substantially uniformthermal effects about valves since the heat transfer mechanism isthrough a vapor that contacts all vessel wall surfaces—and is not anelectrode that is dragged along the vessel wall. In one method of theinvention, the vapor M′ can be propagated from working end 300 whilemaintained in a single location. Thus, the system of the invention maynot require the navigation of the catheter member 305 through tortuousvessels. Alternatively, the working end 300 may be translated along thelumen as energy is applied by means of vapor-to-liquid energy release.

Another advantage of the invention is that the system propagates atherapeutic vapor media M′ from the working surface 320 that can beimaged using conventional ultrasound imaging systems. This will providean advantage over other heat transfer mechanisms, such as ohmic heating,that cannot be directly imaged with ultrasound.

The working end 300 and its method of use as depicted in FIGS. 10-11 canapply therapeutic heat to blood vessel wall to treat chronic vascularinsufficiency (CVI). In this disorder, venous valves are impaired ornonfunctional due in part to vessel swelling and distention proximate tothe valves. The working end 300 as depicted in FIG. 10 can be positionedwithin the vessel to apply heat to the distended vessel wall portions torestore venous valve function. Intraoperative ultrasound can be used toimage the procedure and energy-tissue interaction. Alternatively, MRIcan be used to image the energy-tissue interaction.

In a similar embodiment, a working end 300 as in FIG. 10 can be used toshrink any AVMs (arterial vascular malformations) such as an aneurysm.FIGS. 12-13 illustrate the use of working end 300 to shrink a wide-neckaneurysm 370. It has been found that the ejection of vapor media isreflected by fascia 372 of a blood vessel or other organ lining.Therefore, the shrinkage of the vessel wall occurs very rapidly withouttransfer of energy outside the vessel—as would occur in the applicationof mono-polar Rf energy to a vessel wall. The vessel wall of an AVM alsothickens as it shrinks thus strengthening the wall, which contrast themethod from packing the aneurysm with embolic materials which canfurther distend the vessel wall. The AVM treatment method furthereliminates the use of embolic devices that can migrate. Further, themethod can be used to treat wide-neck or “top-hat” aneurysm which cannoteasily be treated with embolic materials.

In another method of the invention, the working end 300 as depicted inFIGS. 10-11 can be used to apply therapeutic heat to any duct, cavity,lumen or the like in the body to shrink, collapse or damage the anatomicwalls or to fuse together and seal endothelial layers thereof. Forexample, the system and method can be used for tubal ligation in atreatment of fallopian tubes, or for closing microvasculature toterminate blood flow to vascularized diseased tissue, tumors and thelike. Such embolic, vessel closure methods are used to starve canceroustissues and fibroids from blood flow. Such vessel closure methods arealso can be used to starve blood flow from alveoli in a lung volumereduction procedure for treating emphysema. The working end 300 can alsobe introduced within the patient's airways to directly delivertherapeutic heat to airways to cause their shrinkage or collapse tocause lung volume reduction.

The above working ends and methods have been described for use inendoluminal environments wherein the propagation of heated matter(vapor) can function optimally (i) within a fluid in the lumen, (ii) bydisplacing the fluid in the lumen, or (iii) by expanding a space withina collapsed lumen, duct, cavities separated by septae or the like. Itshould be appreciated that the systems and methods of the invention alsocan be used to apply energy directly to the interior of soft tissuevolumes, for example to kill tumors. The heat vapor will propagatewithin extracellular spaces to thereby cause therapeutic heating for thepurpose of creating lesions or killing tissue.

2. Type “B” Thermotherapy Device. FIG. 14 illustrates an alternativeworking end 400 carried by an elongate flexible catheter body 405 of thetype used in interventional cardiology. The working end 400 carries atleast one microchannel structure 415 in working surface 420 as describedabove or applying energy by pressing surface 420 against targetedtissue. FIG. 14 depicts a plurality of microchannel bodies or structures415 in the sidewall of a catheter working end to allow for flexibility,with the catheter body 405 being from 1.0 to 2.0 mm in diameter (notlimiting). The microchannel structure is oriented so that vapor media M′is ejected substantially transverse to the axis 427 of the catheter. Thetargeted tissue T may be veins, myocardium or other cardiac tissue inwhich it is desirable to create a linear transmural lesion or ablationto alter electrical signal transmission in a treatment for atrialfibrillation as is known in the art. As shown in FIG. 14, the workingend 400 is configured with a balloon 430 as is known in the art forpositioning the working end in a treatment location. It is believed thatthe method of the invention can create the desired elongate linearthermal effect in the targeted tissue with greater control over (i) thelateral margins of the treatment path, and (ii) the depth of treatment,when compared to prior art radiofrequency devices that deliver Rf energythat courses through the tissue in an unpredictable manner.

FIGS. 15 and 16 illustrate another embodiment of working end 500 for anendoluminal thermotherapy wherein the catheter body 505 carries interiorchamber 510 and cooperating electrodes 515A and 515B (or a microchannelstructure as in FIG. 8) for applying energy to inflowing liquid media Mto cause it change in phase to vapor media M′. In this embodiment, thetissue-engaging surface 520 and outflow ports 522 are about the exteriorof an expandable structure 524 that is distal to the interior chamber510 and electrodes 515A and 515B. The interior chamber is coupled to thechannel 525 by a flexible film lumen portion indicated at 533 in FIG.16. The expandable structure 524 expands radially outward from thecatheter axis to provide a linear, circumferential lesion. The outflowports 522 are in the channel 525 formed in a temperature resistantlaminate of the thin film polymer layers. The expandable structure canbe an expandable balloon or mechanically actuated structure. In oneembodiment as in FIGS. 15-16, the expandable structure 524 is a balloonof a non-distensible polymer that is expanded by a liquid that can becooled to assist in controlled application of energy to tissue along theline of the outflow ports 522. The balloon inflation lumen is not shownfor convenience. The working surface 520 can create circumferentiallesions in pulmonary veins that are needed in treating atrialfibrillation—the most common form of cardiac arrhythmia (abnormalelectrical signals in the heart), affecting more than 5 million peopleworldwide. It should be appreciated that the flex structure can be conconfigured about a deflectable working end of an instrument to engageabout the exterior of a pulmonary vein for a pulmonary vein ablationtreatment as is known in the art. The method of fabricating the flexiblestructure 524 is described below.

FIG. 17 illustrates another exemplary embodiment 500 with workingsurface 520 and inflow ports 522. This alternative flexible structure524 is preformed for engaging the interior geometry of a lumen or cavityin any body structure or organ. The flexible structure 524 can be anexpandable balloon, a structure expandable by any mechanical mechanismor a shape memory alloy or shape memory polymer, or an open webstructure, for example expanded by gel infusion. Or the device as inFIG. 17 can have an open end 546 and be expanded to net shape of thestructure as vapor media in pushed into channels 525 under pressure. Theflexible structure 524 has a plurality if channels 525 with openings 522therein to allow the exit a vapor phase media M′ that is delivered undercontrolled pressure to the channels. The embodiment of FIG. 17, forexample, can be used for applying energy to the wall 360 of an aneurysm(cf. FIGS. 12-13). It should be appreciated that the flexible structure524 also can take form of a highly elongate sleeve with perforationstherein (not shown) for treating varicose veins. The flexible sleevestructure 524 would be inserted along the targeted length of the vein,and the openings in the sleeve would diffuse the delivery of vapor intoall surfaces of the vessel. The ports 522 can be directed away fromperforator vessels. Such a sleeve 524 can be releasable from theinstrument and of a bioasorbable polymer. The sleeve can be left inplace in the blood vessel. Such a device would be capable of directinghigh pressure flows in the desired direction and expand under inflowpressures of vapor media M′—and then collapse under the force of vesselshrinkage. The device would prevent thermal migration into perforatorsthat extend between surface and deep vein systems.

FIGS. 18A and 18B illustrate the method of making the expandablestructure and working surface 520 of the device of FIG. 17. Thin filmmaterials 532 a and 532 b of a temperature resistant material can beused and bonded (thermally or with adhesives etc.) along weld lines 548to create channels 525. The openings or ports 522 can be laser cut orcreated in cooperating patterns by any suitable means. The ports andchannel dimensions can have cross-sections (or branches) in controlledvaried dimensions or shapes for causing a uniform outflow of vapor phasemedia M′ along the length of an elongate channel.

FIG. 19 illustrates an exemplary cut-away view of a working surface 520and channels 525 and further illustrating the release of the heat ofvaporization to the engaged tissue in the vapor-to-liquid phasetransition as vapor media exits ports 522. The tissue can be anyinterior of any body organ, such as a patient's uterus in an endometrialablation treatment.

FIGS. 20A-20B illustrate an enhanced means of energy delivery to tissuefrom an expandable flex structure 524 similar to that depicted in FIGS.15 and 19. The expandable structure 524 in FIG. 20A carries anadditional conductive surface (electrode) layer indicated at 565 aboutthe surface of the structure proximate the inflow ports 522. It shouldbe appreciated that the conductive surface 565 can be provided in anyworking surface (or interior of any working surface) in the variousembodiments described above. The conductive surface 565 is coupled to anelectrical source and a controller, but is adapted to functionindependently from, or in cooperation with, the electrical dischargesthat convert the liquid media to vapor media. Electrical energy deliveryto surface electrode 565 can be intermittent a high Hz rate of energydelivery to the vaporizing electrodes 515A and 515B, or out of phase,for example. FIG. 20B is a schematic view of the method of theinvention, showing a small portion of expandable structure 524 andchannel 525 pressed against tissue. Vapor media M′ is ejected under highpressure from ports 522 deep into tissue as depicted above in FIG. 19.The media is a high saline content solution that is vaporized in theinstrument working end as described above and injected under highpressure into soft tissue T. It has been found that such vapor injectionmigrates in extracellular spaces between cells 566. The vapor media M′is also conductive (as it consists of a transient ionized plasma) as itextends very deep into soft tissue under the high pressure propagationbefore it condenses and delivers energy to tissue in the phase changerelease. At the time that the vapor media M′ is with in theintracellular spaces 570, it can serve as a gas electrode (or evanescentelectrode) that can conduct high voltage in cooperation with a groundpad until the vapor plume collapses. The method of the invention thuscomprises applying voltage to the gas electrode (from conductive surface565) within the extracellular spaces or deep tissue spaces to applyablative energy to the tissue T. Thus, the phase transition energyrelease can be enhanced by energy delivery via the evanescent electrodemeans. This form of enhanced energy delivery will be uniform about thesurface of the—in effect—gas electrode that evanesces (vanishes) leavingonly dispersed water droplets. By these means, thermal ablation orshrinkage of vessel lumens or soft tissues can be accomplished veryrapidly, under ultrasound visualization. In soft tissue applications, ithas been found that the vapor media can be introduced deep into tissuevolumes through extracellular fluid spaces to apply high energydensities throughout the targeted tissue volume. In effect, theevanescent electrode for micro-second or longer time scale extendsthroughout the tissue—not just contacting the tissue surface as ismono-polar or bi-polar Rf. While the method of applying electricalenergy to the conductive plasma or vapor is shown in soft tissue in FIG.20B, the method applies equally to use in body lumens as in thetreatment of varicose veins as in FIG. 11.

FIG. 21 illustrates an alternative working end 600 that comprises anopenable-closeable jaw structure 602 with first and second jaws 604 aand 604 b that are moveable between a first open position and a secondclosed position to compress engaged tissue together with a releasablepolymer clip-like element 605 carried within the jaws. The clip element605 is adapted for providing sealing functionality in addition to thethermal sealing caused by energy delivery as described above. The sealedvessel also optionally can be transected with a blade 610 in the jawstructure 604 as in known in the art. In this working end, the jawstructure 602 carries a de-matable weldable clip of a heat shrinkablepolymer or a similar shape memory polymer. Preferably, the clip 605 isbiodegradable. In FIG. 21, the surfaces of one or both jaws compriseworking surfaces 620A and 620B that have ports 622 therein from whichvapor media M′ is ejected under high pressure as described above. In oneembodiment, the jaws carry opposing bi-polar electrodes or anotherheating elements to fuse together the ends 624 a and 624 b of clip 605about the tissue. The polymer clip 605 is substantially porous forallowing vapor media M′ to propagate directly through the polymer tointeract with, and further seal the tissue.

FIG. 22A is a phantom view of jaw structure 602 (upper jaw not shown)clamping about a blood vessel 630 with the polymer clip 605 beingcompressed about the tissue. FIG. 22A also shows the ends 624 a and 624b of clip 605 being welded at weld regions indicated at 633. FIG. 22Bcontemporaneously shows the method of shrinking the clip 620 whereinvapor media M′ is ejected into the polymer clip from the jaws to sealthe tissue while at the same time shrinking the biodegradable polymerwithin and about the captured tissue. The scope of the inventionincludes using the vapor media to melt and inject strands or webs ofmelted polymer through the captured tissue. Upon cooling, the polymerand tissue then form an integrated renatured composition for permanentsealing. It should be appreciated that the scope of the inventive clipextends to any form of energy delivery to shrink the clip, for example,Rf energy or laser energy. In one embodiment, the clip has projectingelements or barbs (not shown) to penetrate the tissue and any fascia toassist in vapor penetration into the captured tissue for more rapiddelivery of thermal energy from the vapor to create a tissue seal. Aninstrument can be fabricated that carries a plurality of clips that canbe advanced to the working end, much like a mechanical clip applier. Thepolymer clips also can carry imageable or radiopaque compositions.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Specific features of theinvention are shown in some drawings and not in others, and this is forconvenience only and any feature may be combined with another inaccordance with the invention. Further variations will be apparent toone skilled in the art in light of this disclosure and are intended tofall within the scope of the appended claims.

1. A surgical thermally-mediated therapy for treating tissue comprising causing a controlled vapor-to-liquid phase state change of a selected media in a tissue site by causing a sufficient amount of energy to conduct through the selected media when contained within an instrument such that the selected media increases in volume causing pressurized ejection of the selected media from the instrument into the tissue site thereby applying thermal energy substantially equal to the heat of vaporization of the media to said tissue site causing the vapor media to propagate extracellularly in tissue when in a vapor state and allowing the media to undergo a vapor-to-liquid phase state change and release thermal energy to the tissue and further introducing the vapor media into an interior of a patient's body through an expandable member by engaging a body structure with the expandable member.
 2. A surgical thermally-mediated therapy as in claim 1 wherein the heat of vaporization is in excess of about 500 calories per gram of the selected media.
 3. A surgical thermally-mediated therapy as in claim 1 wherein the vapor-to-liquid phase state change is created within a patient's body after pressurized ejection of the selected media from at least one port of the instrument.
 4. A surgical thermally-mediated therapy as in claim 1 wherein the vapor-to-liquid phase state change is created at a selected depth in tissue after pressurized ejection of the media from the instrument.
 5. A surgical thermally-mediated therapy as in claim 1 wherein the vapor-to-liquid phase state change is created about a flexible working surface deployed in the interior of a body cavity or lumen.
 6. A surgical thermally-mediated therapy as in claim 1 further comprising the step of controlling a parameter of the causing step selected from the class of parameters consisting of controlling the temperature of the vapor-to-liquid phase state change in the selected media, controlling the pressure of the media ejected from a working surface of the instrument, controlling the volume of the media being ejected from the working surface, and controlling the rate of delivery of the media volume being ejected from the working surface.
 7. The method of claim 1 wherein the vapor media collapses in volume upon the vapor-to-liquid phase state change.
 8. The method of claim 1 wherein the vapor-to-liquid phase state change applies thermal energy capable of modifying tissue.
 9. The method of claim 1 wherein the vapor-to-liquid phase state change applies thermal energy capable of at least one of shrinking, sealing, welding and creating lesions in tissue.
 10. The method of claim 1 wherein the vapor media has a temperature of at least 100° C.
 11. The method of claim 1 including controlling at least one of the pressure of the vapor media, the volume of the vapor media, and the duration of a flow of the vapor media.
 12. A method for thermally treating tissue comprising applying a first energy density to a fluid media when contained within a device such that the fluid media increases in volume causing a vapor media and subsequently providing a second energy density being lesser than the first energy density to maintain the vapor media; and expelling the vapor media from the device causing the vapor media to propagate extracellularly in tissue and allow the vapor media to undergo a vapor-to liquid phase state change and release thermal energy in the tissue.
 13. A surgical thermally-mediated therapy for treating tissue comprising causing a controlled vapor-to-liquid phase state change of a selected media in a targeted tissue by modulating energy to apply a first amount of energy to the selected media when contained within an instrument such that the selected media increases in volume and transforms into a vapor media, and subsequently applying a second amount of energy being lesser than the first amount to maintain the vapor media; and controlling propagation of the vapor media using a pressure control system coupled to the instrument to cause pressurized ejection of the selected media from the instrument at a sufficiently high velocity to penetrate the targeted tissue and propagate within extracellular spaces of the targeted tissue to create a lesion in the targeted tissue. 